In recent years, an increase in size of a semiconductor wafer is demanded, and a wire saw apparatus is mainly used to slice a workpiece with this increase in size.
The wire saw apparatus is an apparatus that causes a wire (a high-tensile steel wire) to travel at a high speed, to which a workpiece (such as a silicon ingot) is pressed, to slice the workpiece while applying slurry thereto, thereby slicing the workpiece into many wafers at the same time (see Patent Document 1).
Here, an outline of an example of a conventional general wire saw is shown in FIG. 4.
As shown in FIG. 4, a wire saw 101 mainly includes a wire 102 for slicing a workpiece, wire guides 103 around which the wire 102 is wound, a tension-applying mechanism 104 for giving the wire 102 a tensile force, a workpiece-feeding mechanism 105 for feeding the workpiece to be sliced, and nozzles 106 for supplying a processing liquid (slurry) in which abrasive grains are dispersed and mixed into coolant at the time of slicing.
The wire 102 is unreeled from one wire reel bobbin 107 and reaches the wire guides 103 via the tension-applying mechanism 104 composed of a powder clutch (a constant torque motor 109), a dancer roller (a dead weight) (not shown) and the like through a traverser 108. The wire 102 is wound around this wire guides 103 for approximately 300 to 400 turns, and then taken up by a wire reel bobbin 107′ via the other tension-applying mechanism 104′.
Moreover, each of the wire guides 103 is a roller that has a steel cylinder of which a polyurethane resin is press fitted in the periphery and that has grooves formed at a fixed pitch on a surface thereof. The wound wire 102 can be driven in a reciprocating direction for a predetermined cycle by a driving motor 110.
Moreover, nozzles 106 are provided near the wire guides 103 and the wound wire 102, and the slurry can be supplied to the wire guides 103 and the wire 102 from this nozzle 106 at the time of slicing. This slurry is exhausted as waste slurry after the slicing.
With the wire saw 101, an appropriate tension is applied to the wire 102 with a tension-applying mechanism 104, the wire 102 is caused to travel in a reciprocating direction with the driving motor 110, and a workpiece is sliced while supplying slurry, whereby a desired sliced wafer is obtained.
In slicing a workpiece with a wire saw apparatus as described above, it has been proposed to repeatedly use (reuse) abrasive grains used in this slicing of a workpiece to reduce the cost for manufacturing wafers (Patent Document 2).